IEEE 802.15.4 Protocol Simulation And Analysis

ZigBee is a recently proposed bi-directional wireless communication technology with short distance,low complexity,low power,low data rate and low cost.It is mainly applied in auto-control and remote control.ZigBee,with good application prospect,is designed for the wireless connection and control of small-sized and cheap equipment. Now,researches on ZigBee are mainly focused on its network layer and(MAC) medium access control layer.This paper is mainly about the performance of the MAC sub-layer of 802.15.4 protocol.IEEE 802.15.4 is designed for low-data-rate and small-size wireless personal area networks.It defines the physical layer and MAC layer of ZigBee.This paper begins with introductions about 802.15.4 protocol standard(including its topological structure,protocol stack model and so on),the main principle of physical layer and MAC layer respectively.Then,there is detailed introduction about the channel accessing mechanism of MAC layer and the sloted CSMA/CA mechanism under star topological structure,also,we introduce the Markov modle of this mechanism,which is similar to 802.11 modle.However,in 802.15.4,a backoff counter value of the device decreases regardless of the channel status,and the device senses the channel,i.e. performs clear channel assessment(CCA) twice when the value reaches zero.and then the first CCA and the probability of the second CCA node accessing channel are deduced with mathematical formula.Thus the analytic formula of network throughput is obtained.In this paper,there is brief introduction about NS2 simulation software.In combination with IEEE 802.15.4 Protocol,this paper analyzes the realization method of NS2 simulation software to IEEE 802.15.4 simulation model.Finally,there are results and theoretical analysis of several simulation experiments.In regard to the performance of specific qualities of MAC layer,particular simulation model is adopted in simulation research.Network simulated scene and relative parameter are set.There are further researches about the channel accessing mechanism in beacon-enabled star-topology and NS(network simulator) network simulation tool are used.There are simulations which gives performance of the protocols under different parameters,we analysis the performance of CSMA/CA mechanism with Markov modle and contrast it with actual simulations data.All of the above verify the validity of this rnodel.There are also simulation results and relative theoretical analysis about performance researches under multi-hop network topological_structure.